1. Field of the Invention
The present invention relates to a hybrid integrated circuit device and more particularly, to an improvement of a hybrid integrated circuit device capable of being directly inserted into a socket.
2. Description of the Prior Art
Conventionally, a ceramics substrate or a metal substrate has been used in a hybrid integrated circuit device. However, a metal substrate is mainly used since it has good heat radiating capability and mechanical strength. FIG. 1 is a diagram showing a conventional hybrid integrated circuit device using a metal substrate which is disclosed in Japanese Utility Model Publication No. 3645/1977. Referring to FIG. 1, a metal substrate 1 comprises an aluminum substrate, and an aluminum oxide film 2 is formed on the surface of the metal substrate 1 by anodic oxidation. An insulating layer 3 is formed of resin such as epoxy resin on the aluminum oxide film 2. In addition, copper foil is adhered on the insulating layer 3. The copper foil is etched to be a pattern of a desired shape, so that conductive paths 4 are formed. A plurality of circuit elements 5 are formed on the conductive paths 4. External leads 7 are connected to pads 6 in a tip portion of the conductive paths 4, with constant spacing between the leads.
FIG. 2 is a diagram showing a hybrid integrated circuit device comprising two metal substrates, which is disclosed in Japanese Patent Publication No. 35817/1971. Referring to FIG. 2, metal substrates 9 and 9a provided with circuit elements 8 and 8a are fixed on the upper end and the lower end of a frame member 10, respectively so that the circuit elements 8 and 8a are opposed to each other. External leads 11 and 11a are connected to the ends of the metal substrates 9 and 9a, respectively, with constant spacing.
When such a hybrid integrated circuit device is connected to a print board, external leads 13 of a hybrid integrated circuit device 12 are inserted into holes 15 of a print board 14 and soldered, as shown in FIG. 3. Alternatively, a hybrid integrated circuit device 19 itself comprising a ceramics substrate 18 is inserted into a slit 17 provided in a print board 16, and the substrate 18 and the print board 16 are directly soldered, as shown in FIG. 4. Such a hybrid integrated circuit device is disclosed in Japanese Patent Laying-Open Gazettes No. 92595/1984 or No. 149082/1984.
FIG. 5 is a diagram showing another example of a conventional hybrid integrated circuit device to be inserted into a print board. Referring to FIG. 5, a hybrid integrated circuit device 21 comprises a first substrate 22 and a second substrate 23. The first substrate 22 is adapted such that conductive paths 25 each having a desired shape are formed on a metal substrate 24 having a good heat conductive capability, and circuit elements 26 such as a transistor, a resistor and a diode are provided on the conductive paths 25. The second substrate 23 is adapted such that conductive paths 28 each having a desired shape are formed on an insulating substrate such as a print board 27 as in the first substrate 22, and a large-sized capacitor, a resistor and the like which have been conventionally used as parts externally provided are attached on the conductive paths 28. In he hybrid integrated circuit device 21, the side surface of the first substrate 22 comes into contact with the side surface of the second substrate 23, pads provided in the respective ends of the first substrate 22 and the second substrate 23 are soldered using metallic leads 29, a lid 30 is connected to regions A and B enclosed by dotted lines, so that the first substrate 22 and the second substrate 23 are formed integrally with each other. As shown in FIG. 6, two framed portions 301 and 302 of the lid 30 are connected to the first substrate 22 and a frame portion 303 thereof is connected to the second substrate 23. Such a technique is disclosed in Japanese Patent Publication No. 45078/1982.
However, the conventional hybrid integrated circuit device presents the following various problems. In the structure shown in FIG. 3, the external leads 13 each having a width of about 2 mm derived from the metal substrate 12 is liable to be deformed during the carriage. If and when the deformation is produced, the external leads 13 can not be automatically inserted into the holes 15 of the print board 14 by an automatic inserting apparatus.
In the structure as shown in FIG. 4, since terminals are provided on the surface of the substrate and external leads are omitted, the above described problem can be solved if the substrate to be inserted into the print board comprises an insulating material. However, if and when the metal substrate is inserted into the slit provided in the print board, the slit should be formed to be slightly larger than the outside diameter of the metal substrate so that the metal substrate is easily inserted. Therefore, there is a space between the metal substrate and the slit, so that it is difficult to solder each of the electrodes. In addition, when the metal substrate is inserted, an insulating film of the metal substrate is liable to be torn, so that the electrodes of the metal substrate and the print board are liable to be electrically connected to each other, resulting in a short-circuited state. Therefore, the hybrid integrated circuit device can not be used for high breakdown voltage and large current.
In the structure as shown in FIG. 5 in which the first substrate 22 comprising a metal substrate and the second substrate 23 comprising a print board are formed integrally with each other, the above described problem can be solved because the portion to be inserted into the print board is a print board (insulating material). However, since such an integral type of hybrid integrated circuit device comprising a metal substrate and a print board is formed integrally only by the lid 30, mechanical strength is very low. In addition, since the first substrate 22 and the secnd substrate 23 must be connected to each other by leads, there is a problem in working ability or the reliability of the connecting portion.
Furthermore, since the coefficients of thermal expansion of the metal substrate and the print board significantly differ from each other, the print board is distorted, so that the connecting portion of leads are disconnected.